[X86] Fix pshuflw formation from repeated shuffle mask (PR43230)

Fix for https://bugs.llvm.org/show_bug.cgi?id=43230.

When creating PSHUFLW from a repeated shuffle mask, we have to apply
the checks to the repeated mask, not the original one. For the test
case from PR43230 the inspected part of the original mask is all undef.

Differential Revision: https://reviews.llvm.org/D67314

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371307 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86ISelLowering.cpp

@@ -32041,8 +32041,8 @@ static bool matchUnaryPermuteShuffle(MVT MaskVT, ArrayRef<int> Mask,
   if (!ContainsZeros && AllowIntDomain && MaskScalarSizeInBits == 16) {
     SmallVector<int, 4> RepeatedMask;
     if (is128BitLaneRepeatedShuffleMask(MaskEltVT, Mask, RepeatedMask)) {
-      ArrayRef<int> LoMask(Mask.data() + 0, 4);
-      ArrayRef<int> HiMask(Mask.data() + 4, 4);
+      ArrayRef<int> LoMask(RepeatedMask.data() + 0, 4);
+      ArrayRef<int> HiMask(RepeatedMask.data() + 4, 4);
 
       // PSHUFLW: permute lower 4 elements only.
       if (isUndefOrInRange(LoMask, 0, 4) &&

test/CodeGen/X86/vector-shuffle-256-v16.ll

@@ -4777,23 +4777,14 @@ define <16 x i16> @pr43230(<16 x i16> %a, <16 x i16> %b) {
 ; AVX1-NEXT:    vandps {{.*}}(%rip), %ymm0, %ymm0
 ; AVX1-NEXT:    retq
 ;
-; AVX2-SLOW-LABEL: pr43230:
-; AVX2-SLOW:       # %bb.0:
-; AVX2-SLOW-NEXT:    vpxor %xmm2, %xmm2, %xmm2
-; AVX2-SLOW-NEXT:    vpunpckhwd {{.*#+}} ymm1 = ymm1[4],ymm2[4],ymm1[5],ymm2[5],ymm1[6],ymm2[6],ymm1[7],ymm2[7],ymm1[12],ymm2[12],ymm1[13],ymm2[13],ymm1[14],ymm2[14],ymm1[15],ymm2[15]
-; AVX2-SLOW-NEXT:    vpunpckhwd {{.*#+}} ymm0 = ymm2[4],ymm0[4],ymm2[5],ymm0[5],ymm2[6],ymm0[6],ymm2[7],ymm0[7],ymm2[12],ymm0[12],ymm2[13],ymm0[13],ymm2[14],ymm0[14],ymm2[15],ymm0[15]
-; AVX2-SLOW-NEXT:    vpsrlvd %ymm1, %ymm0, %ymm0
-; AVX2-SLOW-NEXT:    vpshufb {{.*#+}} ymm0 = zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,ymm0[26,27],zero,zero
-; AVX2-SLOW-NEXT:    retq
-;
-; AVX2-FAST-LABEL: pr43230:
-; AVX2-FAST:       # %bb.0:
-; AVX2-FAST-NEXT:    vpxor %xmm2, %xmm2, %xmm2
-; AVX2-FAST-NEXT:    vpunpckhwd {{.*#+}} ymm1 = ymm1[4],ymm2[4],ymm1[5],ymm2[5],ymm1[6],ymm2[6],ymm1[7],ymm2[7],ymm1[12],ymm2[12],ymm1[13],ymm2[13],ymm1[14],ymm2[14],ymm1[15],ymm2[15]
-; AVX2-FAST-NEXT:    vpunpckhwd {{.*#+}} ymm0 = ymm2[4],ymm0[4],ymm2[5],ymm0[5],ymm2[6],ymm0[6],ymm2[7],ymm0[7],ymm2[12],ymm0[12],ymm2[13],ymm0[13],ymm2[14],ymm0[14],ymm2[15],ymm0[15]
-; AVX2-FAST-NEXT:    vpsrlvd %ymm1, %ymm0, %ymm0
-; AVX2-FAST-NEXT:    vpand {{.*}}(%rip), %ymm0, %ymm0
-; AVX2-FAST-NEXT:    retq
+; AVX2-LABEL: pr43230:
+; AVX2:       # %bb.0:
+; AVX2-NEXT:    vpxor %xmm2, %xmm2, %xmm2
+; AVX2-NEXT:    vpunpckhwd {{.*#+}} ymm1 = ymm1[4],ymm2[4],ymm1[5],ymm2[5],ymm1[6],ymm2[6],ymm1[7],ymm2[7],ymm1[12],ymm2[12],ymm1[13],ymm2[13],ymm1[14],ymm2[14],ymm1[15],ymm2[15]
+; AVX2-NEXT:    vpunpckhwd {{.*#+}} ymm0 = ymm2[4],ymm0[4],ymm2[5],ymm0[5],ymm2[6],ymm0[6],ymm2[7],ymm0[7],ymm2[12],ymm0[12],ymm2[13],ymm0[13],ymm2[14],ymm0[14],ymm2[15],ymm0[15]
+; AVX2-NEXT:    vpsrlvd %ymm1, %ymm0, %ymm0
+; AVX2-NEXT:    vpshufb {{.*#+}} ymm0 = zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,ymm0[26,27],zero,zero
+; AVX2-NEXT:    retq
 ;
 ; AVX512VL-LABEL: pr43230:
 ; AVX512VL:       # %bb.0: